1. Technical Field
The present disclosure pertains to devices to assist in loading a boat on a trailer and, more particularly, to a device that automatically centers a boat laterally on a trailer during the loading operation and that is adaptable to existing trailers.
2. Description of the Related Art
Most recreational boats are stored and transported on a trailer that is towed by a personally owned vehicle. Proper positioning of the boat on the trailer is critical to the safe movement of the trailer on the highways. For example, positioning the boat too far to the rear of the trailer will cause the trailer to fishtail and it will raise the rear end of the tow vehicle, reducing traction from the tow vehicle wheels. Positioning the boat too far forward on the trailer will cause too much weight on the hitch, which will drag the rear of the tow vehicle down and make steering more difficult.
Lateral positioning of the boat on the trailer is also critical, not only for safe transportation, launching, and recovery, but also for protecting the hull of the boat. As shown in FIG. 1, most trailers 100 typically have a longitudinal center rail 102 on which are mounted keel rollers 104 for supporting the keel of a boat. The trailer 100 also includes side rails 106, generally parallel to the center rail 102. The side rails 106 typically have bunks 108 or rollers (not shown) or a combination of bunks 108 and rollers for cushioning and stabilizing the boat hull. The exact configuration of the trailer will depend on the type of boat hull.
In some cases, an all-roller trailer is useful for boats having a center keel and left and right sponsons. Alignment of the sponsons with the cradle rollers on the side rails is important to properly support the boat and avoid damage to the hull.
Loading a keel roller trailer requires some skill and agility. With the boat floating near a dock, the trailer is positioned in the water so that the boat and the trailer have their longitudinal axes in general alignment. A winch line is attached to the bow eye on the bow of the boat and the boat is winched onto the trailer with the rollers supporting most or the entire load of the boat. Ideally the boat will remain in alignment with the center rollers. However, wind and waves can cause a boat to easily move off the rollers, requiring quick continual action on the part of those loading the boat. Under less than ideal conditions, this will be a difficult task for an individual to perform alone.
Recently, a new style of trailer has been designed that consists of only bunks and no rollers. In some of these designs, a single vestigial keel roller is located at the stern end of the trailer to deflect the boat upward onto the bunks when loading. Once the boat is fully winched onto the trailer, the stern of the boat no longer contacts the keel roller. Thus, the entire weight of the boat is supported on the bunks and not on the rollers. One disadvantage of this design is that the bunks provide little support for the transom area where the greatest weight of the boat is found, i.e., the engine and fuel. This can place a substantial amount of load on the hull of the boat, which functions as a cantilever to hold up the transom. Because the low-profile trailers are almost completely submerged, the boats are essentiality floated onto the trailer. There is little or no winching of the boat up the trailer because of the substantial friction that would result between the boat hull and the carpeted bunks. Lateral and longitudinal alignment of the boat on the trailer is sometimes more difficult with the float-on trailer design.
Numerous designs have been proposed to assist in loading a boat onto a trailer so that the boat is centered with respect to the trailer, both longitudinally and laterally. For example, U.S. Pat. No. 3,077,277 describes a boat trailer that includes a central roller and a pair of outside rollers that are supported on angularly shaped members that are pivoted on pivot pins. Distal rollers are described as being held in a down position against the trailer by weight and are pushed into engagement with the boat hull as the boat keel bears down on a roller that joins two mutually-opposed arms. Because these arms are coupled together through the single roller, the keel of the boat must bear down on the central roller in order to activate the arms. Hitting only one of the arms will not cause either of the arms to move the hull to a centered position.
In U.S. Pat. No. 4,138,135, a boat trailer is described having a wheeled frame with a tongue extending from a forward end thereof. A boat support is provided on the frame between the opposing sides for supporting the bottom portion of a boat. A pair of spaced-apart arms is pivotally secured to the frame at one side thereof and extends upwardly. A guide rail is secured to and extends between the upper ends of the pair of arms for engagement with one side of the boat. A spring is connected to each of the arms for yieldably urging the guide rail towards the center of the trailer and into engagement with the side of the boat. A second pair of arms is secured to the frame on the other side thereof and extends upwardly therefrom with a second guide rail secured to the upper ends thereof. Thus, the pair of arms in this design are pivotally mounted on the trailer frame and biased towards the center of the trailer by undercarriage springs at a free end of the arms. A boat loading onto this trailer will contact the arms along the side of the hull and scrape against the guide rails as the boat is winched onto the trailer. In addition, the guide rails remain in contact with the boat as the boat is transported, causing wear and chafing on the boat hull.
Hence, there is a need for a mechanically-simple device that automatically centers a boat on a trailer without causing damage to the hull and that is easily adaptable to existing trailers.